1. Field of the Invention
The present invention relates to an input apparatus and an image forming apparatus incorporating the input apparatus.
2. Description of the Related Art
An image forming apparatus such as an electronic copying machine or a multi-functional peripheral comprises an input apparatus including operating keys. A user may input desired numerical values (for example, a number of print copies or a print magnification rate) by means of the input apparatus. The image forming apparatus performs image formation processing under various conditions on the basis of the set values input to the input apparatus.
An up key and a down key are known, for example, as operating keys. In general, prescribed increment values and decrement values are allocated to pressing operations of the up key and the down key, respectively. Whenever a user presses the up key or the down key, a set value of the input apparatus changes by the increment value allocated to the up key or by the decrement value allocated to the down key. Therefore, the user may press the up key and/or the down key to make settings in relation to image formation processing.
A particular input apparatus has a sequential change function for sequentially varying set values. If a user continuously presses the up key or the down key for a prescribed time, then a prescribed increment or decrement value allocated to the up key or the down key is sequentially added or subtracted to/from a set value of the input apparatus. The sequential change function contributes to efficient setting operation in relation to image formation processing.
The sequential change function may also be executed by using a few increment or decrement values. If a user continuously presses the up key for a prescribed time, for example, then a first increment value is sequentially added to a set value of the input apparatus. After the first increment value is added for a prescribed period, a second increment value is sequentially added. Typically, a value of “1” is allocated to the first increment value and a value of “10” is allocated to the second increment value. Therefore, even if the set value of the input apparatus is far from a set value desired by the user, the user may quickly make a setting for image formation processing.
Similarly, if the user continuously presses the down key for a prescribed period, for example, then a first decrement value is sequentially subtracted from a set value of the input apparatus. After the subtraction using the first decrement value for a prescribed period, a second decrement value is sequentially subtracted. Typically, a value of “1” is allocated to the first decrement value and a value of “10” is allocated to the second decrement value. Therefore, even if a set value of the input apparatus is far from a set value desired by the user, the user may quickly make a setting for image formation processing.
As described above, the sequential change function starts in accordance with a length of the pressing time of the up key and/or the down key. Therefore, a user who does not want to use the sequential change function has to press the up key or down key for a shorter period. Furthermore, a user who wants to use the sequential change function has to press the up key or down key for a longer period. The key operations dependent on the length of the pressing period may, however, require complicate setting operation of users.
Key operations dependent on the length of the pressing period may be applied not only to the input apparatus of the image forming apparatus but also to a mobile or car navigation system. In a toggle system which is employed in various mobile telephones and car navigation systems, generally, a few letters or numbers are allocated to one operating key. In a particular apparatus using the toggle system, if a user continuously presses an operating key for a longer period to select a letter or number, thereafter the selected letter or number is fixed as input information. Therefore, the user may set the input information without moving his or her finger to another operating key (for example, an enter key) in order to set the selected letter or number.
A particular input apparatus using the toggle system also changes a display in a display unit of a mobile telephone or car navigation system. For example, if a user presses an operating key for a longer period to select a letter or number, thereafter, as described above, a specific coloured mark is displayed on the display unit 0.2 seconds before the selected letter or number is set as input information.
An input apparatus having the sequential change function is more sensitive than an input apparatus using the toggle system described above about pressing a key (for example, an up key and/or a down key) too long. For example, if a user continuously presses an up key for a longer time inadvertently, then a value which greatly exceeds a set value desired by the user may be input.
The display of a mark on an input apparatus using the toggle system described above may notify a user of switching a function achieved by a shorter pressing operation to a function achieved by a longer pressing operation. Displaying the mark may effectively notify the user of starting the sequential change function which an input apparatus owns. This, however, does not address notification of a change in an increment and/or decrement value after starting the sequential change function.